1. Field of the Invention
The present invention relates to a light-blocking anisotropically electroconductive adhesive film, and to a liquid crystal display device that makes use of the same.
2. Description of the Related Art
The use of liquid crystal display devices as display means for personal computers and the like is becoming increasingly common in recent years, and the use of active matrix type liquid crystal display devices that make use of thin film transistors (TFT) as switching elements is particularly widespread.
As shown in FIG. 1, these active matrix type liquid crystal display devices generally have a COG (Chip On Glass) structure comprising a liquid crystal cell 4 in which a liquid crystal 3 is sealed between a pair of transparent substrates 1 and 2, and a liquid crystal drive-use semiconductor device 5 (such as a LSI chip) connected to the patterned electrodes (not shown) of the substrate 1. The liquid crystal drive-use semiconductor device 5 is connected to an external power source circuit (not shown) by a flat cable 6. Here, the liquid crystal drive-use semiconductor device 5 is connected to the patterned electrodes of the substrate 1 via an anisotropically electroconductive adhesive agent 7xe2x80x2 comprising electroconductive particles dispersed in an insulating adhesive agent, and a backlight (not shown) is disposed on the back surface 1a side of the substrate 1.
With conventional liquid crystal display devices, however, the liquid crystal drive-use semiconductor device 5 generally has an Si-COMOS structure having photoelectric effect characteristics, and therefore when high-energy light is incident on the liquid crystal drive-use semiconductor device 5, leakage of the signal charge may occur, causing a malfunction of the liquid crystal drive-use semiconductor device 5 and resulting in display defects such as illegal characters, missing characters in the display. The light from the backlight is particularly prone to causing malfunction of the liquid crystal drive-use semiconductor device 5.
Consequently, a light-blocking tape (not shown) has been applied to the back surface la of the substrate 1 in order to prevent light (particularly the light from the backlight) from being incident on the liquid crystal drive-use semiconductor device 5 from the back surface 1a of the substrate 1. It has also been proposed that, as an anisotropically electroconductive adhesive agent in the connection of the liquid crystal drive-use semiconductor device 5 to the patterned electrodes of the substrate 1, there is used a dispersion in which electroconductive particles are dispersed in a light-blocking adhesive resin produced by adding a black dye to an insulating adhesive agent (Japanese Patent Application Laid-Open No.07-225391).
However, there is a problem that, when a light-blocking tape is applied to the back surface 1a of the substrate 1, the tact time lengthens and the cost of manufacturing a liquid crystal display device also increases.
Also, although the problems of longer tact time and higher manufacturing costs are improved when a dispersion of electroconductive particles in a light-blocking adhesive resin is used as an anisotropically electroconductive adhesive agent, there remains another problem that the light-blocking effect is insufficiently.
The present invention was conceived in order to solve the above problems of prior art, and an object thereof is to prevent the leakage of signal charges and the malfunction of a liquid crystal drive-use semiconductor device, and to prevent display defects such as illegal characters, missing characters in the display, without lengthening the tact time or increasing the cost of manufacturing the liquid crystal display device, even when the liquid crystal drive-use semiconductor device of the liquid crystal display device is irradiated with high-energy light (particularly light from a backlight).
The inventor perfected the present invention upon discovering that the stated object could be achieved, in the disposition of a liquid crystal drive-use semiconductor device on the transparent substrate of a liquid crystal display device, by using a light-blocking anisotropically electroconductive adhesive film produced by dispersing electroconductive particles and a light-blocking material such as carbon, an inorganic filler or a mixture of these in an insulating adhesive agent, and then forming this dispersion into a film.
Specifically, the present invention provides a light-blocking anisotropically electroconductive adhesive film comprising electroconductive particles and a light-blocking material dispersed in an insulating adhesive agent, wherein the light-blocking material is carbon, an inorganic filler, or a mixture of these.
The present invention also provides a liquid crystal display device comprising a liquid crystal cell in which a liquid crystal is sealed between a pair of substrates, and a liquid crystal drive-use semiconductor device connected to the patterned electrodes of one of the substrates, wherein the liquid crystal drive-use semiconductor device is connected to the patterned electrodes of one of the substrates via the above-mentioned light-blocking anisotropically electroconductive adhesive film.
This and other objects, features and advantages of the present invention are described in or will become apparent from the following detailed description of the invention.